30 subjects with well controlled type 1 diabetes will be recruited for the study. If you agree to participate you will be scheduled for, dietitian visits, and a study visit which will include insulin and glucose infusions, an MRI scan and brain function tests. All visits will be on the Hospital Research Unit (HRU) on the 10th floor of Yale New Haven Hospital. You will be randomized to either the MCT-supplemented diet or the standardized western diabetic diet. If you are on the MCT diet, the MCT oil will be given to you and you will be shown how to incorporate it into your diet. The MCT supplemented diet is for two weeks (with a two gradual transition onto the diet) and the standardized western diet is for two weeks (with a 1 week transition onto the diet). At the end of the study you will be admitted to the Hospital Research Unit for the insulin 'clamp' and MRI scan. A 'clamp' is a procedure which involves insulin and glucose infusions. During a 'clamp' study, the insulin infusion is held constant, while the glucose infusion is adjusted every 5 minutes as needed to maintain the desired blood glucose levels. Compensation for the study is $750.